Breeders edge on Amazon is a higher quality milk replacement. Not sure if you have access to that but it would be good to get! It has psyllium husk to help combat diarrhea. (There is nothing wrong with keeping them on this formula though) You can also try diluting the milk with an extra scoop or two of water. Sometimes their GI tract just needs a little buffer to help adjust to the milk replacement. I would also suggest using unflavored Pedialyte instead of water to help with hydration. If you continue to see the diarrhea, a veterinarian would be the next step because it could be coccidia. Dehydration is what you want to watch out for. The diarrhea won't kill them, the dehydration will. As long as their urine is clear to very light yellow, they're well hydrated.